This invention relates to a device for blocking and unblocking movement of containers, such as bottles, that are guided to move along a longitudinal path on a conveyor.
A known type of blocking device that is located in front of the entrance to a labeling machine for containers uses a freely rotatable star wheel whose arms enter between successive containers which results in the wheel being in continual rotation under the influence of the containers being conveyed. The star wheel is locked when it is desired to stop movement of transportation of the containers without stopping the conveyor. A locking device of this kind, wherein the arms of the star wheel rotate synchronously with the containers, provides for stopping the containers without damage, even at high transportation speeds. One desirable feature of the prior art container blocking device is that it requires relatively low actuating and holding force. A disadvantage is that the arms of the rotating star wheel disturb container movement. For instance, when there is a variation in the spacing between consecutive moving containers, knocking of the containers against each other and against the guide rails on the conveyor occurs and an undesirable increase in noise level results.
Another prior art blocking apparatus for containers such as bottles or conveyors uses a locking arm that is provided with a wedge-shaped lug positioned swingably laterally of the guide rails for alternately moving into blocking position where the lug is interposed in the conveyor path or in a neutral position in which it moves clear of the conveyor path to permit the stream of containers to pass. The blocking device is actuated with a pneumatic cylinder that has a spring return. Because the blocking arm is not synchronized with container movement the lug enters the conveyor path in a random fashion and actually travelling transversely to the direction of container movement. For this blocking device the chance of the containers being crushed or pushed over is increased.